API 5L Pipe: Grades B to X80

Quick Reference

API 5L covers seamless/welded carbon steel pipes for pipeline transport of oil, gas, and water. Grades: B (standard), X42-X80 (high-yield). Specification levels: PSL1 (standard quality), PSL2 (stricter testing, mandatory impact/hardness). Types: SMLS, ERW, LSAW, SSAW. See also pipe types.

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Need a printable version? Download the API 5L Pipe Dimensions Chart for pipe sizes and wall thickness by grade.

API 5l Specification

General Info Pipes API 5l

API 5L is a specification published by the American Petroleum Institute (API) that defines requirements for the manufacture of two product specification levels (PSL 1 and PSL 2) of seamless and welded steel pipes for use in pipeline transportation systems in the petroleum and natural gas industries.

The main features of API 5L pipes are summarized below:

Feature	Details
Types	Both seamless and welded steel pipes. Seamless pipes are produced by piercing a solid billet to form a hollow shell, while welded pipes are manufactured by welding together flat steel plates or coils.
Grades	Designated by the letter “X” followed by a two- or three-digit number. Grade B is the most common for general-purpose applications. X52, X60, X65, X70, X80 are high-yield grades for higher pressures and temperatures. Other grades (X42, X46, X56) are also available.
Chemical Composition	Varies by grade and PSL level. Typical elements include carbon, manganese, phosphorus, sulfur, silicon, and traces of other alloying elements.
Mechanical Properties	Tested for tensile, yield, and elongation. Properties vary depending on grade, wall thickness, and PSL level.
Dimensions and Sizes	Available from 2 inches to 48 inches in diameter. Wall thickness varies depending on grade and PSL level.
Applications	Primarily for transporting oil, gas, and water in pipeline systems. Also used in offshore platforms, refineries, petrochemical plants, and construction projects.
Testing and Inspection	Hydrostatic testing, non-destructive testing (NDT), dimensional inspection, and chemical analysis.

API 5L pipes are widely used in oil and gas for transporting fluids over long distances. Selection depends on grade, size, wall thickness, and PSL level.

The API 5L specification’s latest edition can be read on the API website directly.

API 5L line pipe classification tree

Classification Of API 5l Pipes

API 5L pipes may be classified according to the following criteria:

• Execution: seamless or welded (seamless pipes may be used up to 24 inches, LSAW above 24 inches, ERW up to 20 inches)

• Specification level (API PSL1, PSL2): PSL1 is a standard quality used for pipelines, whereas PSL2 sets more stringent chemical, mechanical properties, and testing requirements

• Surface finish: black, varnish painted, anti-rust oil, galvanized, coated externally (3PL) and/or lined internally

• Pipe ends types: plain, beveled, threaded ends

Advantages Of API 5l Pipes

The main advantages of API 5L pipe are:

• Resistance to cracking forces that may propagate in long pipelines

• Sour service suitability

• Rather inexpensive and long service life (at least grades B, X42)

Size Range API 5l Pipes

API 5L pipes are available in dimensions between 2 to 28″ (seamless execution) and up to 80″ in welded execution (generally, LSAW i.e. longitudinal submerged arc welding).

The API 5L and ASME B36.10 pipe dimensions and weights are, in fact, identical.

API 5l Pipe Chemical And Mechanical Properties

The yield strength of an API 5L pipe is specified with the number that follows the X in the material grade designation (in kilopounds per square inch - i.e. KSI). So, for instance, an API 5L X52 pipe has a minimum yield strength of 52 KSI.

The table shows the chemical composition of API 5L steel pipes PSL1 and PSL2 from Grade A to Grade X70, as well as their mechanical properties. Source: API 5L specification

API 5L PIPE PSL1 Chemical and Mechanical Properties

Grade	C (Max)	Mn (Max)	P (Max)	S (Max)	Tensile Min (Psi x 1000)	Tensile Min (MPa)	Yield Min (Psi x 1000)	Yield Min (MPa)
Grade A25 CL I	0.21	0.60	0.030	0.030	45	310	25	172
Grade A25 CL II	0.21	0.60	0.030	0.030	45	310	25	172
Grade A	0.22	0.90	0.030	0.030	48	331	30	207
Grade B	0.26	1.20	0.030	0.030	60	414	35	241
Grade X42	0.26	1.30	0.030	0.030	60	414	42	290
Grade X46	0.26	1.40	0.030	0.030	63	434	46	317
Grade X52	0.26	1.40	0.030	0.030	66	455	52	359
Grade X56	0.26	1.40	0.030	0.030	71	490	56	386
Grade X60	0.26	1.40	0.030	0.030	75	517	60	414
Grade X65	0.26	1.45	0.030	0.030	77	531	65	448
Grade X70	0.26	1.65	0.030	0.030	82	565	70	483

API 5L PIPE PSL2 Chemical and Mechanical Properties

Grade	C (Max)	Mn (Max)	P (Max)	S (Max)	Tensile (Psi x 1000)	Tensile (MPa)	Yield (Psi x 1000)	Yield (MPa)	CE PCM	CE IIW	Impact Energy (J)	Impact Energy (ft/lb)
Grade B	0.22	1.20	0.025	0.015	60-110	414-758	35-65	241-448	0.25	0.43	T/L 27/41	T/L 20/30
Grade X42	0.22	1.30	0.025	0.015	60-110	414-758	42-72	290-496	0.25	0.43	T/L 27/41	T/L 20/30
Grade X46	0.22	1.40	0.025	0.015	63-110	434-758	46-76	317-524	0.25	0.43	T/L 27/41	T/L 20/30
Grade X52	0.22	1.40	0.025	0.015	66-110	455-758	52-77	359-531	0.25	0.43	T/L 27/41	T/L 20/30
Grade X56	0.22	1.40	0.025	0.015	71-110	490-758	56-79	386-544	0.25	0.43	T/L 27/41	T/L 20/30
Grade X60	0.22	1.40	0.025	0.015	75-110	517-758	60-82	414-565	0.25	0.43	T/L 27/41	T/L 20/30
Grade X65	0.22	1.45	0.025	0.015	77-110	531-758	65-82	448-565	0.25	0.43	T/L 27/41	T/L 20/30
Grade X70	0.22	1.65	0.025	0.015	82-110	565-758	70-82	483-565	0.25	0.43	T/L 27/41	T/L 20/30
Grade X80	0.22	1.90	0.025	0.015	90-120	621-827	80-102	552-705	0.25	0.43	T/L 27/41	T/L 20/30

API 5L Equivalent Grades (ASTM, EN, DIN)

Material grades A53 Gr. B and A106 Gr. B, and also API 5L Gr. X42, are API 5L Gr. B equivalent. It is actually quite common to find on the market pipes that comply, at the same time, with all these specifications (“quadri-norm” marked pipes). While this is true in terms of chemical and mechanical properties, note that the API 5L specification sets more severe requirements and tests than those set for the two equivalent ASTM specifications.

In terms of comparison with EN pipe standards, API 5L Gr. B equivalents are EN 10216-1 P265GH (seamless) and EN 10217-1 P265 (welded) - whereas EN 10216-2 P265 GH is the EN equivalent grade for ASTM A106 Gr. B pipes.

Line Pipe Materials: Werkstoff vs EN vs API

Werkstoff/DIN	EN	API
1.0486 StE 285	-	API 5L Grade X42
1.0562 StE 355	P355N	API 5L Grade X52
1.8902 StE 420	P420N	API 5L Grade X60
1.8905 StE 460	P460N	API 5L Grade X70

High Yield Steel Pipes

Werkstoff/DIN	EN	API
1.0457 StE 240.7	L245NB	API 5L Grade B
1.0484 StE 290.7	L290NB	API 5L Grade X42
1.0582 StE 360.7	L360NB	API 5L Grade X52
1.8972 StE 415.7	L415NB	API 5L Grade X60

API 5l Psl1 Vs. API 5l Psl2

API 5L PSL1 and PSL2 are two specification levels that differ in terms of chemical composition and test requirements. The differences between PSL1 and PSL2 are outlined in the two tables below:

PSL Grade	C (Max)	Mn (Max)	P	S	Si	V	Nb	Ti	Other	CE IIW	CE PCM
PSL 1	0.28	1.40	0.030	0.030	-	-	-	-	-	-	-
PSL 2	0.24	1.40	0.025	0.015	0.45	0.10	0.05	0.04	Yes	0.43	0.25

Test Requirement	API 5L PSL1	API 5L PSL2
Charpy test	None required	Required for all grades
Seamless NDT test	Only if the purchaser specifies SR4	SR4 mandatory
Certification	Certificates when specified per SR15	Certificates (SR 15.1) mandatory
Traceability	Traceable only until all tests are passed unless SR15 is specified	Traceable after completion of tests (SR 15.2) mandatory
Hydrostatic Test	Required	Required

Pro Tip

For pipelines in sour service environments (H₂S), always specify PSL2 with Annex H (Sour Service) requirements. PSL1 doesn’t cover sulfide stress cracking resistance - a critical oversight that has caused pipeline failures.

API 5l Pipe Schedule Chart

Dimensional Range

Wall thickness values are in inches.

NPS	OD	SCH 10	SCH 20	SCH 30	SCH STD	SCH 40	SCH 60	SCH XS	SCH 80	SCH 100	SCH 120	SCH 140	SCH 160	SCH XXS
1/8	0.405	-	-	-	0.068	0.068	-	0.095	0.095	-	-	-	-	-
1/4	0.540	-	-	-	0.088	0.088	-	0.119	0.119	-	-	-	-	-
3/8	0.675	-	-	-	0.091	0.091	-	0.126	0.126	-	-	-	-	-
1/2	0.840	-	-	-	0.109	0.109	-	0.147	0.147	-	-	-	0.187	0.294
3/4	1.050	-	-	-	0.113	0.113	-	0.154	0.154	-	-	-	0.219	0.308
1	1.315	-	-	-	0.133	0.133	-	0.179	0.179	-	-	-	0.250	0.358
1 1/4	1.660	-	-	-	0.140	0.140	-	0.191	0.191	-	-	-	0.250	0.382
1 1/2	1.900	-	-	-	0.145	0.145	-	0.200	0.200	-	-	-	0.281	0.400
2	2.375	-	-	-	0.154	0.154	-	0.218	0.218	-	-	-	0.344	0.436
2 1/2	2.875	-	-	-	0.203	0.203	-	0.276	0.276	-	-	-	0.375	0.552
3	3.500	-	-	-	0.216	0.216	-	0.300	0.300	-	-	-	0.438	0.600
3 1/2	4.000	-	-	-	0.226	0.226	-	0.318	0.318	-	-	-	-	-
4	4.500	-	-	-	0.237	0.237	-	0.337	0.337	-	0.438	-	0.531	0.674
5	5.563	-	-	-	0.258	0.258	-	0.375	0.375	-	0.500	-	0.625	0.750
6	6.625	-	-	-	0.280	0.280	-	0.432	0.432	-	0.562	-	0.719	0.864
8	8.625	-	0.250	0.277	0.322	0.322	0.406	0.500	0.500	0.594	0.719	0.812	0.906	0.875
10	10.750	-	0.250	0.307	0.365	0.365	0.500	0.500	0.594	0.719	0.844	1.000	1.125	1.000
12	12.750	-	0.250	0.330	0.375	0.406	0.562	0.500	0.688	0.844	1.000	1.125	1.312	1.000
14	14.000	0.250	0.312	0.375	0.375	0.438	0.594	0.500	0.750	0.938	1.094	1.250	1.406	-
16	16.000	0.250	0.312	0.375	0.375	0.500	0.656	0.500	0.844	1.031	1.219	1.438	1.594	-
18	18.000	0.250	0.312	0.438	0.375	0.562	0.750	0.500	0.938	1.156	1.375	1.562	1.781	-
20	20.000	0.250	0.375	0.500	0.375	0.594	0.812	0.500	1.031	1.281	1.500	1.750	1.969	-
22	22.000	0.250	0.375	0.500	0.375	-	0.875	0.500	1.125	1.375	1.625	1.875	2.125	-
24	24.000	0.250	0.375	0.562	0.375	0.688	0.969	0.500	1.219	1.531	1.812	2.062	2.344	-
30	30.000	0.312	0.500	0.625	0.375	-	-	0.500	-	-	-	-	-	-
32	32.000	0.312	0.500	0.625	0.375	0.688	-	-	-	-	-	-	-	-
34	34.000	0.312	0.500	0.625	0.375	0.688	-	-	-	-	-	-	-	-
36	36.000	0.312	0.500	0.625	0.375	0.750	-	-	-	-	-	-	-	-
42	42.000	-	0.500	0.625	0.375	0.750	-	-	-	-	-	-	-	-

API 5L Pipe Outside Diameter Tolerance

Outside Diameter D	Diameter Tolerance (Pipe Body)	Diameter Tolerance (Pipe End)	Out-of-Roundness (Pipe Body)	Out-of-Roundness (Pipe End)
610 mm (24 in) to 1,422 mm (56 in)	± 0.01 D (max +4.0 mm / 0.160 in)	SMLS: ± 2.0 mm (0.079 in), Welded: ± 1.6 mm (0.063 in)	0.015 D (max 15 mm / 0.6 in for D/t ≤ 75)	0.01 D (max 13 mm / 0.5 in for D/t ≤ 75)
> 1,422 mm (56 in)	As agreed	As agreed	As agreed	As agreed

Notes:

• Pipe end includes a length of 100 mm (4.0 in) from each end
• For SMLS pipe, tolerances apply for wall thickness up to 25.0 mm (0.984 in); thicker pipes require agreement
• For pipe with D ≥ 219.1 mm (8.625 in), tolerances may be based on calculated or measured inside diameter
• For D/t > 75, tolerances are by agreement

API 5L Pipe Wall Thickness Tolerance (WT)

API 5L Seamless Pipe Wall Thickness Tolerances

Wall Thickness t	Tolerance
≤ 4.0 mm (0.157 in)	+0.6 mm (0.024 in) / -0.5 mm (0.020 in)
> 4.0 mm (0.157 in) to < 15.0 mm (0.591 in)	± 0.1 t
≥ 15.0 mm (0.591 in)	± 1.5 mm (0.060 in)

Notes:

• If a smaller minus tolerance is specified, the plus tolerance increases to maintain the tolerance range
• For pipe with D ≥ 355.6 mm (14 in) and t ≥ 25.0 mm (0.984 in), wall thickness may locally exceed the plus tolerance by 0.05 t, provided mass tolerance is not exceeded
• Plus tolerance does not apply to the weld area

API 5l Monogram

Manufacturers of steel pipes may request API an audit to assess their capabilities to comply with the API 5L standard.

Pipe mills that pass the API audit successfully are awarded an API monogram.

API lists in a composite index the names of the factories that have passed the audit successfully. The monogram has an expiration date. The API monogram is therefore similar to the franchising scheme, however, API does not have any financial benefit from the certification of pipe mills, nor does it take any liability and the performance of the certified mills and products.

How To Order API 5l Pipes

Parameter	API 5L Pipe Ordering Details
Qty	Feet or lengths
Size	NPS (Outside Diameter) and Schedule Number (Average Wall Thickness)
PSL	PSL 1 or PSL 2
Material Grade	Grade A, Grade B, X42, X46, X52, X60, X70, X80, etc
Execution	Seamless or Welded execution
Surface finish	Bare, Black, FBE, etc
Marking requirements	If different from the API 5L Specification
Pipe coating or lining requirements	To protect the pipe from erosion and corrosion, depending on the fluid to be conveyed
Manufacturer	Approved Manufacturer List (AML), or Country of Origin restrictions
Sour service	Yes / No

We recommend purchasing the API5L specification from the API store to get a complete understanding of this topic.

Field Note

When inspecting API 5L pipe deliveries, always check the stencil markings against the MTCs. Mismatched heat numbers are more common than you’d think - and traceability breaks mean you can’t use the pipe on a critical pipeline.

Top Manufacturers Of API 5l Pipes

The following are major producers of API 5L line pipes:

Tenaris

Tenaris is a global manufacturer of steel pipes and related services for the energy industry. They produce seamless and welded API 5L pipes across all standard grades.

TMK (Pipe Metallurgical Company)

TMK is one of the largest producers of tubular products for oil and gas. They manufacture API 5L pipes in both seamless and welded execution across multiple grades.

Nippon Steel Corporation

Nippon Steel Corporation is a major Japanese steelmaker producing API 5L line pipes, particularly in high-grade LSAW execution for large-diameter pipeline projects.

ArcelorMittal

ArcelorMittal is a multinational steel manufacturer with operations in more than 60 countries. Their product range includes API 5L pipes for pipeline applications.

JFE Steel Corporation

JFE Steel Corporation is a Japanese steelmaker that manufactures API 5L pipes, including high-grade X65-X80 for offshore and deepwater pipeline projects.

Vallourec

Vallourec is a major producer of seamless steel pipes and tubes for oil and gas exploration and production. They supply API 5L seamless line pipes in grades B through X80.

Severstal

Severstal is a Russian steel and mining company that produces API 5L pipes among its range of steel products.

United States Steel Corporation (U.S. Steel):

U.S. Steel is one of the largest steel producers in the United States and manufactures API 5L seamless and welded pipes for pipeline and energy applications.

Other notable producers include EUROPIPE (Germany), Sumitomo Metals (Japan), and Welspun (India). Manufacturer selection should consider product quality, certifications, lead times, and delivery track record.

Common Mistake

Accepting pipes without verifying the API monogram validity date. The monogram expires, and expired monograms are not valid. Always check the API composite list before accepting delivery.

Top Chinese Manufacturers

China is a major source of API 5L pipes for both domestic and export markets. Notable Chinese producers include:

Manufacturer	Specialty
Baosteel Group Corporation	One of China’s largest steel producers; manufactures API 5L seamless and welded pipes across all standard grades.
Hunan Standard Steel Co., Ltd.	Manufacturer and exporter of API 5L seamless and welded steel pipes in various grades.
Tianjin Pipe (Group) Corporation (TPCO)	One of the largest seamless steel pipe manufacturers in China; produces API 5L in grades B through X80.
Shaanxi Huitong Special Steel Co., Ltd.	Produces API 5L seamless and welded steel pipes and tubes.
Shandong Huitong Steel Pipe Manufacturing Co., Ltd.	Manufacturer of API 5L seamless steel pipes.
Wuxi Huayou Special Steel Co., Ltd.	Produces API 5L steel pipes and tubes.
Jiangsu Yulong Steel Pipe Co., Ltd.	Manufacturer of API 5L pipes in seamless and welded execution.
Zhejiang Huatian Stainless Steel Manufacturing Co., Ltd.	Produces API 5L and other steel pipes.

When sourcing API 5L pipes from Chinese mills, verify the API monogram status, review third-party inspection reports, and confirm compliance with the required PSL level.